부산대학교 도서관

Introduction: Type B Aortic Dissection (TBAD) is a lethal disease. The tissue mechanical property is of great importance for estimating TBAD rupture risk. This study sought to characterize the mechanical properties of stiffness and strength of dissection flap and adventitia tissues from patients with chronic TBAD.Methods: Aortic tissue removed from 23 patients undergoing open repair of thoracoabdominal aortic aneurysms secondary to chronic TBAD was analyzed. Uniaxial testing was performed on the flap (circumferential [Circ] n=11, axial n=8) and on the adventitia (Circ n=7, axial n=6 ). The uniaxial lower tangent modulus (uLTM), uniaxial higher tangent modulus (uHTM) and ultimate tensile strength (UTS) were obained for each sample from stress-strain relation (Fig. 1a). We also perfromed biaxial tension testing (BTT, in Circ and Axial) of the flap (n=7) and adventitia (n=9). BTT is closer to the in vivo loading condition than uniaxial testing. Since BTT usually achieves lower maximum stress, here only the biaxial lower tangent modulus (bLTM, Fig. 1b) was obtained.Result: The uLTM of the dissection flap (Fig. 1c), and bLTM of the flap and adventitia (Fig. 1d) in Circ are significantly larger than those in Axial (p=0.006, 0.011, and 0.008, repsectively). In Circ (Fig. 1d), the bLTM of the adventitia is larger than that of the flap (p=0.027). The flap UTS in Circ is larger than that in Axial (Fig. 1f, p<0.001). In Axial, adventitia UTS is larger than flap UTS (Fig. 1f, p=0.001).Conclusions: The adventitia is stiffer and stronger than the dissection flap in patients with cTBAD. These biomechanical data corroborate the surgical axiom of including the adventitia in surgical repair of aortic dissections. Furthermore, the flap and adventitia in Circ are stiffer than those in Axial. These findings may provide insight into the ability of the aorta to maintain its wall integrity in the setting of hypertension and aneurysmal disease, and provide foundations for estimating the risk of TBAD.